Power over ethernet emergency lighting system and method of detecting power loss of a link segment thereof

ABSTRACT

A system for providing power over Ethernet emergency lighting is disclosed. The system includes a rechargeable battery pack that is charged without interfering with data signals present on a power over Ethernet link that provides normal lighting. The system includes a power loss monitor for monitoring the presence of normal lighting power present on a power over Ethernet link without interference.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/516,896, filed on Jul. 19, 2019, issuing as U.S. Pat. No. 10,903,682on Jan. 26, 2021, which is a continuation of U.S. patent applicationSer. No. 15/903,862, filed on Feb. 23, 2018, issued as U.S. Pat. No.10,361,583 on Jul. 23, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/432,381, filed on Feb. 14, 2017, issued as U.S.Pat. No. 9,941,737 on Apr. 10, 2018, which is a continuation of U.S.patent application Ser. No. 15/073,492, filed on Mar. 17, 2016, issuedas U.S. Pat. No. 9,609,706 on Mar. 28, 2017, which claims the benefit ofand priority to Provisional Application No. 62,135,006, filed on Mar.18, 2015, the entire contents of which are hereby incorporated byreference herein, for all purposes.

TECHNICAL FIELD

The present invention relates to emergency lighting systems, and moreparticularly to providing emergency lighting systems powered by powerover Ethernet (“POE”) systems.

BACKGROUND ART

Lighting systems, particularly in commercial settings, are subject to anumber of strict functional requirements set by various standard settingorganizations. Among these is the requirement that emergency lighting beprovided in the event of a loss of building power. These mandatedemergency power systems must provide backup lighting for a predeterminedperiod of time, must be tamper, fire, flood and earthquake resistant,and must meet certain other functional requirements. Conventionally,emergency lighting systems are provided as self-contained unitsinstalled in light fixtures, which include batteries charged by adedicated A/C power line.

The promulgation of IEEE standards for power-over-Ethernet (“POE”),combined with the ubiquity of RJ45 Ethernet cabling in modern businessand residential buildings, provides alternative means for buildinglighting. There are at present two ratified IEEE standards for POE: IEEE802.3af and IEEE 802.3at. An Ethernet port operating in accordance withthe IEEE 802.3af standard is capable of supplying 12.95 Watts to powereddevices (“PDs”) over a POE link. IEEE 802.3at defines the POE+ standard,which enables the delivery of up to 25.5W over a POE link. Currentefforts are underway to promulgate more advanced POE standards (e.g.,POE+ and POE++), which will specify equipment capable of supplying up to90 W over a POE link.

Realizing a POE link over the physical connections of Cat5+ Ethernetcable is done according to one of two alternatives, illustratedschematically in FIG. 1 As can be seen in FIG. 1 , an RJ45 Ethernetcable 105 carries 8 conductors grouped as 4 twisted pairs (110 a,b and115 a,b), with two twisted pairs (e.g., 110, 115) forming acommunication link for a first port (transmit and receive), and with thetwo remaining twisted pairs available as spares (e.g., 115 a,b). InAlternative A, a DC voltage is supplied over data lines, across centertaps on internal signal coupling transformers (120 a,b) connected acrossthe pair of conductors on each of the transmit and receive twistedpairs. The DC voltage is then supplied from the center taps of anotherpair of transformers (125 a,b) across the receive-side twisted pairs forthe transmit and receive lines. This DC voltage is supplied to a powereddevice 130 on the receive end of the link. In Alternative B of the POEstandard, DC voltage is supplied through the unused or spare twistedpairs. Newer and proposed POE standards provide more power and fasterdata using all 8 conductors. These methods require 4 Data transformers,where Power is imposed on all pairs.

In recent years, with the declining cost and increased efficiency oflight emitting diodes (“LEDs”), LED lighting has begun to replacefluorescent lighting in commercial settings. FIG. 2 is a schematicrepresentation of a conventional LED lighting installation powered by aPOE link, or more precisely, an Ethernet cable referred to under the POEstandards as a Port Data Link Segment. 48V DC nominal is supplied overthe link by power sourcing equipment (“PSE”) 205 (e.g., a POE switch,hub or midspan injector). The power is superimposed on data transmissionwire pairs of an Ethernet link segment (e.g., 210 a, b) carried on aCATnx (e.g., Cat 5+) cable. The link segments (210 a,b) supply power toa Powered Device (PD), for example, POE luminaire Lighting LED Driver220, where the power is intelligently extracted (i.e., separated fromthe data) at the PD. Power extraction occurs at a POE Lighting LEDDriver 220, which appears to the PSE as any conventional PSE operatingaccording to the POE standards. Power is then delivered by the driver220 to LED lamps 225. In certain conventional implementations, driver220 and LED lamps 225 are co-located in an LED luminaire 215, which isinstalled, for example at a ceiling light fixture.

In a typical AC Power System, certain luminaires (i.e., light fixtures)are designated as also emergency luminaires, which by code and acceptedbuilding practice must maintain illumination upon a loss of AC power.Luminaires are complete with all the necessary luminaire components;e.g., light sources (lamps, such as LEDs), a ballast or lamp powersupply such as an LED driver), etc. If a luminaire is to also act as anemergency luminaire, it is outfitted with additional hardware enablingit to drive all or a portion of the light sources (i.e., lamps) foremergency illumination in emergency-mode operation—a condition triggeredby the loss AC power. Thus, the existing lamps in these luminaires areused both for normal lighting when AC power is supplied, and also forillumination in emergency-mode operation when normal AC power fails.

SUMMARY OF THE INVENTION

The invention is directed to an emergency lighting luminaire powered bya POE network connection deployed, for example, in the context ofexisting POE lighting. Embodiments of the invention include a firstpower enabled Ethernet link segment, a rechargeable emergency batterypack, a normal lighting LED driver, an LED lamp, and a power lossmonitor. In certain embodiments, the first power enabled Ethernetconnects to a POE port link segment. Further, the rechargeable emergencybattery pack contains a battery charger, a rechargeable battery, and anemergency LED driver, which is connected to one input of a relayingdevice. Moreover, the other input of the relaying device is electricallyconnected to a normal lighting LED driver, which drives an LED lightingarray under normal operating conditions and the output of the relayingdevice is connected to the LED lamp.

Embodiments of the invention further include a power loss monitor, whichdetermines whether power is being provided over the normal lighting LEDdriver or whether there has been an interruption of power. When thepower loss monitor detects a loss of power from the normal lighting LEDdriver, a controller, which is connected to the power loss monitor,connects one input of the relaying device to the LED lamp. However, whenthe normal LED driver has power, the other input of the relaying deviceis connected to the LED lamp.

In certain embodiments, the emergency lighting luminaire furthercomprises a second POE input connectable to a power POE port linksegment. When the first POE input is connected to the battery charger,the second POE input is connected to the normal lighting LED driver.Further, the first and second POE inputs are included in the emergencybattery pack, which further includes a POE output that is connected tothe second POE input by a pass-through loop. The POE output is alsoconnected to the normal lighting LED driver. In other embodiments, thepower loss monitor communicates with the normal lighting POE linkpass-through loop.

In certain embodiments, the relaying device, adapted to form anelectrical connection between the battery and the LED lighting array (ora stand-alone emergency LED array), is an electro-mechanical switch. Inother embodiments, the relaying device is a solid-state device.

In certain embodiments, the POE emergency luminaire including thebattery charged by a port link segment that is entirely independent fromthe port link segment driving normal lighting. In other embodiments, thesystem includes a battery charged with DC power via an auxiliary poweroutput interface from the normal lighting LED driver, which itself isdriven by a single POE port link segment. In other embodiments, thesingle POE port link segment supplies power to an emergency backupbattery pack, which then supplies normal lighting power via a powerbridge.

In certain embodiments, the power loss monitor is connected to a firstconductor on a first POE data pair of a POE port link segment, and thepower loss monitor is connected to a second conductor on a second datapair of the same POE port link segment. The power loss monitor capableof determining when a POE port link segment loses power, but withoutinterfering with data communications on that link segment. In otherembodiments, the power loss monitor further includes an opto-coupler, aresistor, and a Zener diode. The power loss monitor regulates currentflowing through the LED of the opto-coupler based on whether the voltagedifferential between the first and second conductors exceeds apredetermined threshold. Further, the power loss monitor includesferrite beads capable of filtering connected between the rectifyingdiode bridge and the first and second conductors. Moreover, the firstand second conductors are connected to POE link segment over the firstpower over Ethernet input.

Embodiments of the invention also provides a system for providingemergency backup power in a POE luminaire, which has a connection to aPOE link segment, a lamp driver and a lamp. The system further containsa power loss monitor connected to detect a loss of POE power in the POElink segment and an emergency backup battery and lamp driver connectedto supply power to the lamp when the power loss monitor detects a lossof POE power in the POE link segment.

Moreover, embodiments of the invention provides a method of detectingpower loss in a POE link segment, comprising the steps of detecting adifferential DC voltage between a first conductor in a first data pairon a POE link segment and a second conductor in a second data pair onthe same POE link segment. In certain embodiments, the step of detectingthe differential DC voltage includes detecting a decrease in currentthrough a measurement device when the differential DC voltage between afirst conductor in a first data pair on a POE link segment and a secondconductor in a second data pair on the same POE link segment drops belowa predetermined threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood by referring to thefollowing Detailed Description of Specific Embodiments in conjunctionwith the Drawings, which are embedded in the Detailed Description below.

FIG. 1 is a schematic illustration of a conventional Power-over-Ethernetlink.

FIG. 2 is a schematic illustration of a conventional LED-based POElighting system.

FIG. 3 is a schematic illustration of a POE emergency lighting luminairehaving two POE port links according to an embodiment of the invention.

FIG. 4 is a schematic illustration of an emergency POE battery pack foruse with the luminaire of FIG. 3 .

FIG. 5 is a schematic illustration of a POE emergency lighting luminaireusing an auxiliary power link according to an embodiment of theinvention.

FIG. 6 is a schematic illustration of an emergency POE battery pack foruse with the luminaire of FIG. 5 .

FIG. 7 is a schematic illustration of a POE emergency lighting luminaireusing a port power bridge according to an embodiment of the invention.

FIG. 8 is a schematic illustration of an emergency POE battery pack foruse with the luminaire of FIG. 7 .

FIG. 9 is a schematic diagram of a POE interface according to theinvention.

FIG. 10 is a circuit diagram of a power loss monitor according to anembodiment of the invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

A detailed description of preferred embodiments of the invention is setforth below.

References throughout this specification to “one embodiment,” “anembodiment,” “a related embodiment,” or similar language mean that aparticular feature, structure, or characteristic described in connectionwith the referred to “embodiment” is included in at least one embodimentof the present invention. Thus, appearances of the phrases “in oneembodiment,” “in an embodiment,” and similar language throughout thisspecification may, but do not necessarily, all refer to the sameembodiment. It is to be understood that no portion of disclosure, takenon its own and in possible connection with a figure, is intended toprovide a complete description of all features of the invention.

In addition, the following disclosure may describe features of theinvention with reference to corresponding drawings, in which likenumbers represent the same or similar elements wherever possible. In thedrawings, the depicted structural elements are generally not to scale,and certain components are enlarged relative to the other components forpurposes of emphasis and understanding. It is to be understood that nosingle drawing is intended to support a complete description of allfeatures of the invention. In other words, a given drawing is generallydescriptive of only some, and generally not all, features of theinvention. A given drawing and an associated portion of the disclosurecontaining a description referencing such drawing do not, generally,contain all elements of a particular view or all features that can bepresented is this view, for purposes of simplifying the given drawingand discussion, and to direct the discussion to particular elements thatare featured in this drawing. A skilled artisan will recognize that theinvention may possibly be practiced without one or more of the specificfeatures, elements, components, structures, details, or characteristics,or with the use of other methods, components, materials, and so forth.Therefore, although a particular detail of an embodiment of theinvention may not be necessarily shown in each and every drawingdescribing such embodiment, the presence of this detail in the drawingmay be implied unless the context of the description requires otherwise.In other instances, well known structures, details, materials, oroperations may be not shown in a given drawing or described in detail toavoid obscuring aspects of an embodiment of the invention that are beingdiscussed.

FIG. 3 shows an emergency POE luminaire 300 using two POE port linksegments 305 a, b. The luminaire 300 includes two POE inputs 310 a, b,each POE input being connected respectively to a POE port link segment305 a, b. POE port link segments 305 a, b are connected to unillustratedpower sourcing equipment, such as a POE enabled such, hub or midspan(i.e., injector). Both POE inputs 310 a, b are electrically connected toPOE emergency battery pack 315. Battery pack 315 includes POE interface320, which is connected to a first POE port link segment 310 a via input305 a. Battery pack 315 also includes a battery charger 325, battery330, and LED driver 335. POE interface 320 extracts DC power (supplied,for example, as 48 Vdc) from the POE port link segment 310 a, andsupplies that power to battery charger 325. Battery charger 325 stepsdown the voltage supplied by POE interface 320 and performs certaincurrent conditioning functions.

An exemplary POE interface suitable for use as POE interface 320 isillustrated in additional detail in FIG. 9 . The POE interface 900 ofFIG. 9 performs several functions. First, it extracts DC power from RJ45connector 905 via the center-tap of the data transformers 910 a, b whichare connected on the primary-side to a POE link segment. Additionally,POE interface functions to separate data flow 915 from power flow and tocouple both data and power to the application 920 (i.e., the functionalcomponents of the PD containing the POE interface). POE interface 900includes an RJ45 connector 905, data transformers 910 a, b withcenter-tap primary, bridge rectifier(s) 925, signature circuitry 930,classification circuitry 935, an intelligent switch over-currentisolation “active-switch” with pass-FET 940, and a DC/DC isolation powerconverter 945.

After the POE interface 900 extracts DC power from the RJ45 connectorvia the center-taps of the data transformers 910 a, b, the power iscoupled to an input diode bridge 925 which protects the circuitry withinthe PD from being connected to a reverse polarity input voltage byaccepting either positive or negative polarity inputs. Power is then“intelligently” supplied to the PD by the PSE (connected on the otherside of the POE link segment) via a communications protocol via the“physical” (PHY) layer compliant to the IEEE 802.3xx standard. DC poweris supplied by the PSE at a nominal target voltage of 48 Vdc. The“power-up” process follows a sequence where, once a PD is connected tothe end of the POE Link Segment via the RJ45 connector 905, the PSEstarts to raise the voltage from 0 Vdc based on the IEEE 802.3xxstandard, with pre-determined levels, timing, and current detection. Thesequence follows from left-to-right, from Signature to Classification toIsolation to DC/DC to Application.

The first phase of the sequence (detection) of the powering sequenceoccurs when the PSE polls the connected PD to determine if it providesthe correct impedance signature. The PSE accomplishes this by ramping upa current limited (5 mA) detection voltage (from 2.5 V to 10 V) acrossthe designated pairs of CAT-x wires (at about a 2 ms repetition rate)and measuring the voltage and the current at the end of the ramp time.If the PSE detects the proper signature impedance in accordance with theIEEE 802.3xx standard, it determines that there is a valid PD at the endof the link. The PSE then proceeds to the next step in theprocess—Classification. Classification is the process where the PD“indicates” to the PSE the required power range it will need. There are5 categories (classes). During classification, the PSE induces 15.5-20.5Vdc, limited to 100 mA, for a period of 10 to 75 ms responded by acertain current consumption by the PD, indicating its power class. Thesequence advances to the next step where the PSE raises the voltage to34 Vdc, and the PD “closes” the “Turn-on” switch (the Pass-FET in 940)but slowly controls inrush current consumption (of over 350 mA) within50 ms. Once this step is completed, the PSE ramps the voltage up to 48Vdc for the DC/DC isolation power converter 945 to supply power to theapplication 920. The application 920 for the POE emergency battery packof FIG. 3 is battery charger 325.

Battery charger 325 is a high-frequency switch-mode power supply,designed to manage battery charging according to the battery chargecapacity, size, terminal voltage, type, and other influencing factorswith regards to energy usage and regional market regulations orrestrictions. In certain embodiments, battery charger 325 is an isolated“Flyback” topology high-frequency switch-mode current source type withdigital over analog control. Other topologies are used in otherembodiments to best manage the chosen battery, such as, a “Buck”converter or a “Buck-boost” converter, or other topology, and eithercurrent sourcing or current-over-voltage sourcing may be used during thecharging process, pulse-charge or linear-charge, constant-rate ormulti-rate. Battery charger 325 may be designed to charge differenttypes of batteries, such as, NiCd, NiMH, Pb-based, or Li-based. Wherebattery 330 is a NiCd battery, battery charger 325 is a “smart-charger”capable of supplying 1 to 3 Watts of power during recharge phase, andless than 1 Watt during maintenance-mode charging. In normal operationbattery charger 325 provides a trickle charge, (supplied at 1.2 to 20Vdc and a nominal current range of between 30 mA and 300 mA for typicalNiCd type batteries; however, these voltage and current values depend onthe type, pack design, and charge state of battery 330) to battery 330.

Battery 330 supplies DC power to LED driver 335 at 2.4 to 24 Vdc, withthe most typical voltages 6 to 19.2 Vdc depending on the type of LEDluminaire 345. In certain embodiments, battery 330 is a rechargeableNiCd battery having a reserve capacity of 2.5 to 3.0 amp-hours at 6 to19.2 Vdc. Other embodiments use other battery types, such as NiCdbatteries having a reserve capacity of 1.5 to 4.0 amp-hours at 2.4 to 24Vdc (1.2 Vdc/cell), or Lithium iron phosphate (LiFePO4) batteries havinga reserve capacity of 0.5 to 3.0 amp-hours at 3.0 to 3.6 Vdc/cell.

In certain embodiments, LED driver 335 is a switch-mode power converterthat powers the LED lamp(s) with power (Energy/time) provided by battery330, and supplies DC current at a nominal 0.08 to 2.0 A over a voltagerange from 10 to 60 Vdc to LED lamps 345 via relaying device 340. TheLED current supplied in these embodiments is a pure DC current, or DCcurrent with low AC ripple.

In alternative embodiments, LED driver 335 is a DC-DC “Flyback” topologyhigh-frequency switch-mode power supply with Pulse-Width Modulation(PWM) control (digital or analog), where the output Voltage or Currentor Power are regulated. In these embodiments, PWM current is passedthrough the LEDs. Other topologies are used in other embodiments, suchas, a “Buck” converter or a “Buck-boost” converter, or Half-Bridgeconverter, or Full-Bridge converter, or other topology. The typical LEDpower levels for Emergency-Mode operation range from 3 to 25 Watts, withother power levels possible. The typical LED voltage ranges from 10 to60 Vdc for Class 2 operation, with other voltages possible.

LED lamps 345 vary in operating voltage, current, power, and lightoutput, depending on the embodiment. The typical LED lamps for LEDfixtures are offered over a large range of different types for largearea lighting range in voltage from 10 to 60 Vdc for Class 2, and highervoltages for non-class 2. LED fixture lamp arrays & modules operate overa wide range of current levels from 0.08 Adc to 3 Adc. Colortemperatures for LED lamps 345 range from 2500 K (warm-white) to 6000 K(bright-white), depending on the embodiment.

Relaying device 340, in one embodiment, is an electromechanical switchthat alternatively couples one of two inputs (341, connected toemergency battery pack 315, or 342, connected to normal lighting LEDdriver 350) to LED lamps 345. Use of an electromechanical switch asrelaying device 340 is advantageous because it results in near-zeroinsertion loss for battery pack 315, i.e., when battery pack 315 is notconnected, normal lighting LED driver 350 is connected to led lamps 345with minimal electrical resistance. This invention or any embodimentsare not limited to only an electromechanical switch as the relayingdevice, alternate relaying devices such as diodes or solid-stateswitches or other types are possible and within the scope of theinvention.

POE power link segment 305 b is electrically connected through thebattery pack's second POE input 305 b to normal lighting LED driver 350via normal lighting POE input 355. Normal lighting LED driver 350includes a POE interface 360, which extracts DC power available on thesecond POE link segment 310 b (i.e., 48 Vdc), and supplies it to LEDdriver 365. Like emergency backup LED driver 335, LED driver 365 hasdifferent operating parameters depending on the embodiment. In oneembodiment, LED driver 365 is optimized to operate over a large range ofvoltages from 10 to 60 Vdc for Class 2, and higher voltages fornon-class 2. Such a driver can supply a large range of current levelsoperate over a wide range of current levels from 0.08 Adc to 3 Adc. ThePOE power levels are limited currently to about 55 Watts each, however,with future developments allowing up to near 90 Watts, additional higherpower LED drivers and higher power luminaires are possible and withinthe scope of the invention. LED driver 365 is electrically connectedthrough output 370 to an input of relaying device 340, and then,depending on the state of relaying device 340, to LED lamps 345.

In normal lighting operation, LED lamps 345 are driven from normallighting LED driver 350, which takes DC power from power link segment305 b, which is supplied in a pass-through fashion through emergencybattery pack 315. Emergency battery pack 315 further includes a powerloss monitor 375, which monitors the status of power being supplied tothe second POE input 305 b by monitoring pass-through loop 380 betweenthe second POE input 305 b and POE output 385. POE output 385 is in turnconnected to normal lighting driver POE input 355.

When the luminaire 300 of FIG. 3 is in normal lighting mode, relayingdevice 340 is set such that its second input 342 is electricallyconnected to LED Lamps 345. This results in current being supplied fromnormal LED lighting driver 350 to LED lamps 345. As will be discussedfurther in relation to the battery pack of FIG. 4 , when power lossmonitor 375 detects a power down condition on pass-through loop 380,relaying device 340 switches states such that its first input 341, whichis connected to emergency LED driver 335 to LED lamps 345.

The luminaire described with respect to FIG. 3 has certain advantages.Because the luminaire uses two, independent POE link segments, one forcharging the backup battery and another for driving the LED lamps undernormal lighting conditions, the luminaire of FIG. 3 minimizes thelikelihood of corrupting or otherwise interfering with the fidelity ofdata being transmitted or received over the second POE link segment 305b. This may be helpful if link segment 305 b is being used forcommunication as well as for the supply of DC power. Moreover, existinglighting and building codes, for example, NFPA 70 National ElectricalCode, NFPA 101 Life-Safety code, and UL 924 Standard for SafetyEmergency Lighting and Power Equipment, require that, for emergencybackup lighting, unswitched power (i.e., normal lighting power), bemonitored at the entry point of a luminaire. This is accomplished in theluminaire of FIG. 3 , because power loss is monitored at input 310 b toluminaire 300. This arrangement is also advantageous because it locatesall critical components of the emergency luminaire within the luminaire,which minimizes the risk of hazards that might cause failure of theemergency lighting luminaire due to tampering, smoke, flood, fire,icing, vandalism, or other adverse conditions.

FIG. 4 schematically illustrates an emergency battery pack 400 useablein a luminaire having two independent POE links, for example, luminaire300 discussed above in reference to FIG. 3 . The battery pack 400includes two POE inputs, one for battery charging 410 a, and a secondfor power for normal operation conditions 410 b, which is passed throughbattery pack 400 to a POE output 485. The charging POE input isconnected to POE interface 420, which extracts DC power from theconnected POE link and supplies that power to battery charger 425.Battery charger 425, in normal operating conditions, charges battery430. Battery 430 supplies LED driver 435, which is connected to a firstinput 441 of a relaying device 440, which in certain embodiments is anelectro-mechanical switch. Relaying device 440 alternatively connectseither its first input 441 or its second input 442 to an output 443electrically coupled to non-illustrated LED lamps. Second input 442 ofrelaying device 440 is connected to input 444, which when battery pack400 is installed, receives normal lighting power from a normal lightingLED driver.

The battery pack 400 of FIG. 4 also includes a power loss monitor 475,which detects a loss of power on pass-through loop 480. Upon detectionof a loss of power by power loss monitor 475, a controller 490, which incertain embodiments is a microprocessor in communication with anon-illustrated memory, switches relaying device 440 such that its firstinput 441 is connected to output of the battery pack 443. Controller490, in certain embodiments, includes additional functionality. Forexample, upon detecting a power loss condition, controller may send asignal via I/O ports 495 a, b to an external or internal signaling orindication device, indicating the detection of power loss conditions. Incertain embodiments, controller 490 sends a derangement signal to one ofports 495 a, b upon detection of a loss of normal lighting power. Insome embodiments, derangement signal illuminates an LED to alert usersthat the emergency lighting system has been triggered. In someembodiments, controller 490 sends additional data communications signalsto ports 495 a, b to be connected to other external devices, forexample, over Ethernet links connected to ports 495 a, b. Such signalsmay inform remote Ethernet connected devices of the status of batterypack 400, the occurrence of a power loss condition, and any other usefulinformation. Controller 490 also optionally receives input controlsignals via ports 495 a, b. Exemplary input control signals include testsignals to simulate a power loss condition to test the functionality ofbattery pack 400, or status queries for controller 490. In certainembodiments, controller 490 communicates with other external devicessuch as a normal lighting LED driver (e.g., 350 in FIG. 3 ) or a datalogger.

FIG. 5 is a schematic illustration of an alternative embodiment of aluminaire using an emergency lighting battery pack fed by auxiliarypower directed from a normal lighting LED driver. Unlike the embodimentof FIG. 3 , the embodiment of FIG. 5 relies on only a single POE portlink segment 505, with supplies DC power (as well as datacommunications, in some embodiments) to normal lighting LED driver 510through POE input 515. As in the embodiment of FIG. 3 , POE interface520 extracts DC power from POE link segment 505 and supplies it to LEDdriver 520. In normal lighting operating conditions, LED driver 525supplies driving current to LED lamps 585 through driver output 530 andfirst input 582 of relaying device 580, which will be described infurther detail in connection with battery pack 550.

The embodiment of FIG. 5 also includes battery pack 550 for supplyingemergency power to LED lamps 585 in the event of a power loss conditionin normal LED lighting driver. Like the embodiment of FIG. 3 , batterypack 550 includes a battery charger 565, which charges battery 570,which drives LED driver 575. The output of LED driver 575 is connectedto a first input 581 of relaying device 580, which alternativelyconnects its first or second inputs 581, 582 to LED lamps 585, such thatpower can be switched from normal lighting LED driver 530 to batterypack 550 in the event of the detection of a normal lighting power losscondition.

Unlike the embodiment of FIG. 3 , the luminaire 500 of FIG. 5 does notuse two POE link segments. Instead, a one-port method is enabled byextracting a low level of DC power from the normal lighting powersupplied to normal lighting LED driver 510 by an auxiliary power outputinterface 535. This power is extracted from the POE fed DC supply beingcoupled to an aux power output interface 535 after the POE Interface 520has separated Data flow from Power flow, or in other implementations atany point before or after the interface. In one embodiment, DC power (0to 3 W) is extracted at the nominal POE voltage of 48 Vdc (36-57 Vdcrange) on POE input 515 to driver 510, and is supplied via output 540,auxiliary power link 545 and power input 555 to battery pack 550. The DCpower interface converter 560 controls (i.e., by limiting in-rushcurrent, filtering noise bi-directionally, and buffering) the 48 Vdcsupply that feeds the supplied power to operate Battery Charger 565.

In accordance with this arrangement, the input voltage of the BatteryCharger 565, in one embodiment, is a nominal 48 Vdc (36-57 Vdc range).The output voltage of the Battery Charger 565, in the same embodiment,typically floats to the nominal battery voltage of Battery 570 of 9.6Vdc+/−20% fully charged, or simply Vbatt float for other particularbatteries. Chargers in other embodiments are capable of supporting otherbattery voltages within a typical range of between 2.4 and 24 Vdc. Thebattery charge current is dependent on charge level, time, application,and battery type, ranging from 0.0 Adc (no charge current) up to 1 C,where C is the battery charge capacity equivalent current expressed inAdc. Values of C supported by embodiments of the invention include 1.2A, 1.5 A, 2 A, 2.2 A, 2.5 A, 3 A, 3.5 A, 4 A, with C=3 A being the mosttypical for POE lighting.

The input of the LED Driver 575 is coupled to the Battery 570 at thebattery nominal terminal voltage +/−20% and ranges to 1 V/cell at theend of the discharge cycle. In a typical embodiment, the typical batteryvoltage, fully charged, is approximately 9.6 Vdc for an 8-Cell NiCdbattery. The input current of the LED Driver 575 is dependent on batteryvoltage, output power, and efficiency. The typical input current of theLED Driver 575 is approximately 1.7 Adc for a 9.6 Vdc battery voltage.

For emergency-mode operation LED driver 575 is connected to first input581 of relaying device 580, which connects to LED lamps 585. The LEDDriver 575 is capable of driving LED lamps 585 over a large range ofvoltages from 10 to 60 Vdc for Class 2, and higher voltages fornon-class 2, and over a large range ranging from 0.08 Adc to 2 Adc, withhigher current levels possible in the future. The POE power levels arelimited currently to about 55 Watts each, however, with futuredevelopments allowing up to near 90 Watts.

In the embodiment of FIG. 5 , a normal lighting loss of power isdetected by power loss monitor 590 in battery back 550. In thisembodiment, loss of power at normal lighting LED driver 510 (forexample, because power has been lost on POE port link segment 505results in loss of power on auxiliary power link 545 such that the powerloss can be detected at battery pack 550. This maintains the advantagesof the system described in reference to FIG. 3 , where power may be lostat any point up to the luminaire without impacting the functionality ofthe emergency illumination system.

As in the embodiment of FIG. 4 , the battery pack 550 includescontroller 595, which, at least, switches relaying device 580 inresponse to detection of a power loss condition. Controller 595optionally has additional functions in additional embodiments, which aredescribed more fully below in reference to FIG. 6 .

FIG. 6 schematically illustrates an emergency battery pack 600 useablein a luminaire having one POE port link segment, for example, luminaire500 discussed above in reference to FIG. 5 . Like the battery packdescribed in FIG. 4 , battery pack 600 includes controller 655, but alsoincludes I/O ports 665 a, b for two-way communications with externaldevices, for example, for receiving test signals and status queries, andfor sending status data and a derangement signal in the case of a powerloss condition.

FIG. 7 schematically illustrates a POE backup luminaire 700 according toanother embodiment of the invention. In the embodiment of FIG. 7 , likethat of FIG. 5 , the luminaire receives power over a single POE portlink segment 702. Unlike the embodiment of FIG. 5 , POE link segment 702is first connected directly to battery pack 705. A POE port interfacewith integral power bridge (“IIPB”) 715 extracts a low level of DC powerto provide to battery charger 720, which charges battery 725, to supplyLED driver with power to drive LED lamps 750 in the event of a powerloss condition as has been described.

IIPB 715 operates to provide an isolated data link, as will as a DCpower link from link segment 702 to the normal lighting LED driver. IIPBalso extracts or bridges a low level amount of power from link segment702 to battery charger 720. From a systems level perspective, linksegment 702 is a dedicated link segment for normal lighting purposes,data and power over one single link segment. IIPB 715 enables thecapability to maintain this single-purpose usage, while power is usedalso to power the battery charger 720. Power is provided from the PSEnormal power supply via link segment 702 to the normal lighting LEDdriver 705 according to the IEEE 802.xx POE standard, which supportsactive and intelligent communication between the PSE normal power supplyand the normal lighting LED driver 705. IIPB 715 is an intelligent powerextractor, extracting a low level of power from the normal lighting POElink segment to provide power to battery charger 720, in such a way soas to not disturb or interfere with the data communications or the powerflow between the PSE and the normal lighting driver 705. Each POE portlink segment is intended as a dedicated link between the PSE and the PD(in this case, the normal lighting LED driver). The IIPB is transparentin this process and does not communicate over the POE Port Link Segment702.

As in previous embodiments, controller 747 detects a power losscondition and switches relaying device 740 to connect battery 725 to ledlamps 750. Unlike in previously described embodiments, a power losscondition is detected in the battery pack 705. Power loss monitoring isa shared function, with initial monitoring integrally within the IIPB715, and additionally supported by the electronic Controls 747.

FIG. 8 schematically illustrates an emergency battery pack 800 having apower bridge 810, useable in a luminaire having one POE port linksegment connected to input 805. Such a luminaire is usable as a batterypack in, for example, luminaire 700 discussed above in reference to FIG.7 . Like the battery pack described in FIGS. 4 and 6 , battery pack 800includes controller 840, but also includes I/O ports 845 a, b fortwo-way communications with external devices, for example, for receivingtest signals and status queries, and for sending status data and aderangement signal in the case of a power loss condition.

FIG. 10 illustrates a pair of power loss monitor circuits, each of whichis usable for the power loss monitor 375 described above in reference toFIG. 3 . FIG. 10 illustrates two circuits, 1005, which detects powerloss on Port 1 (between pins 1 and 3) of an attached RJ45 POE cable1015, and 1010, which detects power loss on Port 2 of the same cable(between pins 4 and 7). In the discussion to follow, reference will bemade to the Port 1 circuit 1005 primarily, which involves circuitcomponents R22, D21-D24, D25, D26, U4, U5, FB5, and FB6; however, itshould be understood that the discussion likewise applies to theadjacent circuit 1010 for Port 2.

As is set forth above with respect to FIG. 1 , power extraction in POEtypically occurs on a powered device's data transformer (e.g., 125 a and125 b in FIG. 1 ), specifically from the “center-tap” of a twisted pairtransformer winding (the PD data transformer primary). As shown in FIG.1 , these terminations (referenced to the RJ45 connector) are pin sets(1,2-3,6) and (4,5-7,8). Turning now to FIG. 3 , because the luminaireof FIG. 3 uses two separate POE links (a separate dedicated emergencylink for battery charging and a separate link for the normal lightingLED driver), access to the PD data transformer (located at POE interface360, for example) for the normal lighting POE link is not provided forthe power loss monitor (e.g., 375). Embodiments of the invention solvethis problem by recognizing that the POE voltage is DC and of equalvalue (ideally) on each of the pin-pairs; i.e., Vpin1=Vpin2, andVpin3=Vpin6, etc. Therefore, the nominal voltage Vpin1−Vpin3=+/−48 Vdc.Likewise, the nominal voltage Vpin2−Vpin6=+/−48 Vdc. Likewise, thenominal voltage Vpin4−Vpin7=+/−48 Vdc. Likewise, the nominal voltageVpin5−Vpin8=+/−48 Vdc. A terminating circuit across any of thesepin-sets (i.e., any pair of pins, where each pin is associated with itsown twisted pair in the cable) is then used to measure and detect thepower on a given port. Minimum data interference can be achieved becausethe resulting dc current i_monitor is relatively low and is of a commonmode dc signal.

One novel advantage of this method and system of detecting a loss of POEpower is the minimization of noise and interference that is achievableby DC current flow differentially only between two pair sets (across thesupply terminals differentially imposed) rather than across any onedigital data pair. The low level DC current is imposed as a common-modecurrent for each data pair, but is differentially imposed between datapair sets. The data pairs respond only to differential signals withinthe pair, and reject common-mode signals. Furthermore, data signals areAC, differential-mode for each twisted pair; therefore, AC interferenceto the data signals is minimized by the “non-differential-mode” ofi_monitor, rather it is common-mode DC across pair sets. What is more,this power loss monitor connectivity method remains valid for bothAlternatives A or B shown in FIG. 1 .

In the circuits of FIG. 10 , port power “On” or “Off” is detected byOpto-Coupler U5 (or like-wise U6 on port 2), where the output signal isa digital signal—Port power “On” status results in current flow in theOpto-Coupler sufficient to drive the output transistor of theopto-coupler to the “On” state. The Opto-Coupler is a “High-Gain”device, where minimum current through the opto-coupler's input LED isdesired, which allows for the detection of power on with very low poweruse. Additionally, opto-coupler U5 provides galvanic isolation(isolating functional sections of electrical systems to prevent directcurrent flow), which provides maximum prevention of noise interferencebetween circuits.

In the circuits of FIG. 10 , current is provided through theopto-coupler U5 via bridge rectifier 915, resulting in the power lossmonitor being compatible for each of the possible polarityimplementations (see D21-D24 of circuit 1005 of FIG. 10 ).

The circuit of FIG. 10 includes two Zener diodes in series (D25, D26)connected to opto-coupler U5 as shown. The first Zener diode D25 isconnected in series with the Opto-Coupler's input LED, which providesintended current flow only when the port input operating voltage exceedsthe D25's breakdown voltage (Vb), thereby providing a voltage referencemeans. When the voltage across a D25 exceeds its Vb value, D25 “turnson” and passes current according to the familiar I-V curve for a Zenerdiode, causing current flow to increase sharply as the voltage continuesto rise above Vb. In the arrangement of FIG. 10 , as the POE port inputoperating voltage rises from 0 Vdc up to the nominal value of 48 Vdc,the component values are selected such that at the desired port voltagethe circuit “turns on” sharply allowing current to flow and then toincrease in magnitude as the input port voltage exceeds Vb. In thismanner, the POE power “On” threshold voltage (the minimum InputOperating Voltage of 37 Vdc) is “measured” and a circuit response isinitiated. Zener diode D25 and its functions are understood by thoseskilled in the art to be easily implemented additionally utilizingIntegrated Circuits and programmable devices.

As can be seen in FIG. 10 , the circuit additional and optionallyincludes a series resistor R22, the Opto-Coupler's input LED, and thetwo series Zener Diodes D25, D26. The total Zener diode breakdownvoltages (the two Zener diode Vb values together) are selected to setthe circuit response (the point at which the digital output of theOpto-coupler U5 changes states). Therefore, the circuit comprised ofseries resistor R22, the Opto-Coupler, and the two series Zener Diodes(D25 & D26), form a functional Analog-to-Digital converter.

The circuit of FIG. 10 additional and optionally includes certainfeatures that provide hysteresis. Hysteresis is the time-based functionof a system's output on present and past input variables. The dependencearises because the history affects the value of an internal state. Topredict its future output state, either its internal state or itshistory must be known. In the circuit of FIG. 10 , as the input voltageapproaches the circuit “threshold voltage,” there becomes an increasingdepletion of “noise immunity” where the output state change as afunction of the input voltage level becomes highly unstable. The designof FIG. 10 provides sufficient values of hysteresis to mitigate againstcircuit response instability and ambiguity.

The circuit of FIG. 10 includes an isolated hysteresis sub-circuit,comprised of components D26, U5, and feedback from non-illustrated PowerMonitoring Control circuitry, contained, for example, in the controllersdescribed above. Isolation is accomplished by use of Opto-coupler U5.Hysteresis is accomplished by setting the “turn-on” voltage level higherthan the “turn-off” voltage level. An exemplary method of accomplishingthis, implemented in one embodiment of the invention, is to first splitthe total Zener diode breakdown voltage Vb total into two separate Zenerdiodes (D25 & D26). The breakdown voltage Vb D26 is a small fraction ofthe total; furthermore, Vb_D26<Vb_D25. As the port input voltage risesfrom 0 to 48 Vdc, with the circuit “turn-on” threshold voltage set at 37Vdc, the Opto-coupler responds with a circuit response by changingdigital states on its output transistor. The output of Opto-coupler U4feeds a monitor and a control circuit which then couples back into thePower Loss Monitor in the form of information feedback via Opto-couplerU5. The output of U5 (a transistor) is connected to bypass Zener DiodeD26. As U5 changes states from “off” to “on,” its output transistordiverts current flow around D26, collapsing the D26 Zener voltage tonear zero volts. The total Zener Diode breakdown voltage is thus reducedby the value of Vb_D26. The circuit “threshold” voltage is reset to alower voltage (30 Vdc), known as the “Falling input voltage.” The outputstate of Opto-coupler U4 will not change states until the input voltageis falling and decreases to less than 30 Vdc. The differential voltagebetween “turn-on” (37 Vdc) and the “turn-off” voltage (30 Vdc) is 7 V,and is referred to as the hysteresis voltage.

The power loss monitor circuit of FIG. 10 also includes features toattenuate cross talk and filter noise. Ferrite beads FB5 & FB6 areplaced such that they function as low-pass filters, attenuatinghigh-frequency noise energy. They are in effect series inductors in thecircuit. Therefore, the ferrite beads block high-frequency current,enabling attenuation of high-frequency noise coupled into the datapairs.

While the preferred embodiments of the present invention have beenillustrated in detail, it should be apparent that modifications andadaptations to those embodiments may occur to one skilled in the artwithout departing from the scope of the present invention.

What is claimed is:
 1. A POE (“power over Ethernet”) emergency lightingsystem comprising: a POE input configured to connect to a first POE portlink segment, the POE input connected to a POE interface, which isoperable to extract DC power from the first POE port link segment,wherein the POE interface is further operable to supply low level DCpower to a battery charger, and wherein the POE interface is alsooperable to supply a relatively higher level of DC power to a normallighting lamp driver; a rechargeable battery configured to receive DCpower from the battery charger and to supply DC power to a backup lampdriver; a controller configured to detect a loss of normal operatingpower and to generate control signals in response to a detection of aloss of the normal operating power; a switch having a switch outputalternatively connected to the backup lamp driver and the normallighting lamp driver in response to the control signals.
 2. The systemof claim 1, wherein the switch is an electromechanical relay.
 3. Thesystem of claim 1, wherein the switch is a solid state switch.
 4. Thesystem of claim 1, wherein the POE interface includes an integral powerbridge that supplies the normal operating power extracted from the firstPOE port link segment to the normal lighting lamp driver.
 5. The systemof claim 4, wherein the POE interface is further operable to detect aloss of the normal operating_power on a connected first POE port linksegment.
 6. The system of claim 1, wherein the controller is operable todetect a loss of the normal operating_power on a the first POE port linksegment by detecting a loss of the normal operating power supplied bythe POE interface to the battery charger.
 7. The system of claim 1,wherein the switches output is connected to the normal lighting lampdriver when the controller does not detect a loss of normal operatingpower, and when the controller detects a loss of normal operating power,controller generates control signals to cause the switches output to beconnected to the backup lamp driver.
 8. The system of claim 1, whereinthe POE interface includes a POE output connectable to a second POE portlink segment operable, when connected, to supply the relatively higherlevel of DC power to the normal lighting lamp driver.
 9. The system ofclaim 1, further comprising one or more LED lamps connected to theswitch output, and wherein the normal lighting lamp driver and thebackup lamp driver are LED drivers.
 10. A POE (“power over Ethernet”)emergency battery pack configured to connect to a POE port link segmentand a lamp, the battery back comprising: a POE input configured toconnect to the POE port link segment, the POE input connected to a POEinterface, which is operable to extract DC power from a the POE portlink segment, wherein the POE interface is further operable to supplylow level DC power to a battery charger, and wherein the POE interfaceis also operable to supply a relatively higher level of DC power to anormal lighting lamp driver; a rechargeable battery connected to receiveDC power from the battery charger and to supply DC power to a backuplamp driver; a controller connected to detect a loss of power from thefirst POE port link segment and to generate control signals in responseto a detection of a loss of normal operating power; a relaying devicehaving a first input configured to connect to the backup lamp driver, asecond input, and an output alternatively connected to the first andsecond inputs in response to the control signals, the output beingconnectable to a lamp.
 11. The battery pack of claim 10, further anintegral power bridge that provides a level of DC power on an outputthat is suitable for providing normal operating power to a lamp driverconnectable to the lamp.
 12. The battery pack of claim 11, wherein thePOE interface includes the integral power bridge, and wherein, theoutput is a POE output connectable by a POE link segment to a normallighting lamp driver.
 13. The battery pack of claim 12, wherein thesecond input of the relaying device is connected to an output of thenormal lighting lamp driver.
 14. The battery pack of claim 10, whereinthe relaying device is an electro-mechanical relay.
 15. The battery packof claim 10, wherein the relaying device is a solid state switch.